Look back rule question

[jmkupka]

"A batter-runner who rounds first base toward second base may stop, but then must immediately without stopping return to first or attempt to advance non-stop to second base."

Your opinion, please, at which point you will ring up the batter-runner:

R1 on 3b, batter-runner (base on balls) rounds first and trots slowly nonstop toward 2nd (no action by the pitcher holding the ball in the circle). Batter-runner gets tired of waiting for a throw and takes the one stop (that she has coming to her) and immediately heads nonstop back to 1st.

Is she out? Must the one stop be made right after rounding 1st, or can it be anywhere between the 2 bases?

Sorry if this is an old worn out topic...